In a conventional ultrasonic flow rate measuring device, plural partition plates that partition a flow path are latched in slits provided in both side plates of the flow path in order to construct a multilayer flow path. Plural flat flow paths are formed (for example, see PTL 1).
FIG. 10 is an overall perspective view of a conventional ultrasonic flow rate measuring device described in PTL 1, FIG. 11 is a sectional view in a direction 11-11 when the ultrasonic flow rate measuring device in FIG. 10 is cut by a plane A, FIG. 12 is an exploded perspective view of a multilayer flow path member of the ultrasonic flow rate measuring device, and FIG. 13 is a sectional view in a direction 13-13 when a side plate in FIG. 12 is cut by a plane B. As illustrated in FIGS. 10 to 13, a multilayer flow path member 100 includes partition plates 103 that partition measurement flow path 101 into plural flat flow paths 102 and frame 105 that supports edge portions 104 along fluid flowing direction in partition plates 103. That is, frame 105 is formed into a rectangular box shape by side plates 106 and 107, top plate 108, and bottom plate 109. Partition plates 103 are horizontally retained between side plates 106 and 107 at predetermined intervals in a vertical direction.
Plural slits 110 are provided in an inner surface of each of side plates 106 and 107 in order to retain partition plates 103 at predetermined intervals. Slits 110 are provided at equal intervals in a direction orthogonal to a fluid flow such that sectional areas of flat flow paths 102 are equalized.
While multilayer flow path member 100 is fitted in multilayer member attaching portion 111 of measurement flow path 101, ultrasonic wave passing apertures 113 are provided in side plates 106 and 107 of frame 105 of multilayer flow path member 100 located in ultrasonic propagation path 112. Filter member 114 is attached to aperture 113. Plural flanges 115 are provided in edge portion 104 of partition plate 103.
In slits 110 provided in side plates 106 and 107 of frame 105, through-hole 116 is made at a position corresponding to flange 115 of partition plate 103. An end face of partition plate 103 is exposed through through-hole 116. Because through-hole 116 is made every flange 115, flange 115 is bonded and fixed to frame 105 using bonding agent 117.
In assembling multilayer flow path member 100, after flange 115 is inserted in through-hole 116, side plates 106 and 107 and partition plate 103 are bonded and fixed to each other using bonding agent 117. Therefore, the number of components increases and it takes a long time to assemble multilayer flow path member 100, which results in a problem of a cost increase. Bonding agent 117 overflows onto a side of flat flow path 102 to generate a disturbance of a flow in flat flow path 102, which possibly degrades accuracy of flow rate measurement. Thus, from the viewpoint of the assembly of partition plate 103 and the measurement accuracy, there is room for improvement in the conventional ultrasonic flow rate measuring device.
PTL 1: Unexamined Japanese Patent Publication No. 2009-210525